Performing drive tests in order to collect radio measurements in a wireless network is not only expensive and time consuming, it may also fail to reach all geographical areas in the network e.g. indoors. That is why Minimisation of Drive Tests, MDT, was introduced in 3rd Generation Partnership Project, 3GPP. The objective is to configure the User Equipment, UE, to perform radio measurements, in idle or connected mode, and then report them to the network. Geographical position measurements are integral to this procedure since a main intention of MDT is to map the radio performance of a cellular network geographically. Hence MDT reports a geographical location together with radio conditions (e.g. reflected by UE measurements) that are related to this geographical position—otherwise MDT would be meaningless.
A plurality of methods and techniques exist to determine a position, or location, of a wireless device, e.g. a UE. Some examples are Cell ID positioning (CID), Enhanced Cell ID (E-CID), CID plus Timing Advance (TA), Time Of Arrival (TOA), Time Difference Of Arrival (TDOA), Observed TDOA (OTDOA), Global Position System (GPS), and fingerprinting positioning.
Radio signal strength and quality measurements comprise power-based radio signal measurements such as signal strength or quality that may be used for positioning to derive the distance, e.g. based on the pathloss estimation, or as Radio Frequency, RF fingerprints. This may be performed by wireless devices or radio nodes or a combination thereof.
Examples of timing measurements are time of arrival, round trip time (RTT), time difference of arrival, Rx-Tx, timing advance, and propagation delay. Timing measurements in general help to obtain more accurate distance information compared to distance estimation based e.g. on radio signal strength or pathloss measurements due to the fading fluctuations of the latter. Timing measurements are particularly common for positioning, although they may very well serve more general network purposes as well. Timing measurements may be performed by wireless devices or radio nodes or both, e.g. the later applies for two-direction measurements such as RTT.
The angle of arrival, AoA, measurement standardised for Long Term Evolution, LTE, is defined as the estimated angle of a UE with respect to a reference direction which is the geographical north, positive in the clockwise direction. This measurement may be performed by the eNodeB or the UE.
Generally, the positioning and MDT requirements cause a lot of activity at least for the wireless devices, but also for the network nodes. Determining the location, or position, as well as MDT measurements require substantial processing at the wireless device and also extensive signalling within the communication network. This in turn cost power for the wireless device resulting in shortened battery life and also substantial resource usage of the communication network.